Conductor wire connection method and conductor wire connection structure

Abstract

To provide a connection method for efficiently connecting a plurality of conductor wires to a plurality of electrodes formed on a substrate, and a connection structure capable of connecting the plurality of electrodes formed on the substrate at an extremely small pitch to the plurality of conductor wires while suppressing generation of a solder bridge.SOLUTION: A connection method for connecting a plurality of conductor lines 211,221,231,241,251 to a plurality of electrodes 11 to 15 formed on a substrate 1 includes an arrangement step of arranging a solder foil 30 between the plurality of electrodes 11 to 15 and the plurality of conductor lines 211,221,231,241,251, and a soldering step of soldering the plurality of electrodes 11 to 15 and the plurality of conductor lines 211,221,231,241,251 by melting the solder foil 30 while pressing the plurality of conductor lines 211,221,231,241,251 against the substrate 1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a connection method for connecting a plurality of conductor wires to a plurality of electrodes formed on a substrate, and a connection structure for connecting a plurality of electrodes formed on a substrate to a plurality of conductor wires. [Background technology]

[0002] Conventionally, the miniaturization and high performance of electronic components and electronic devices have led to a trend toward narrower pitches between electrodes on substrates to which conductor wires are connected. Patent Document 1 describes a method for forming conical solder bumps with a high aspect ratio (solder paste height / solder paste bottom diameter) by discharging solder paste multiple times from a direction perpendicular to the land on the substrate. Patent Document 2 describes a bonding method in which a core wire is placed on multiple pre-soldered conductive joints, covered with a light-transmitting sheet, and the pre-solder is heated and melted by irradiating light toward the light-transmitting sheet. Patent Document 1 describes that the land spacing (pitch) is preferably 0.4 mm or more, and Patent Document 2 describes that the pitch of the conductive joints is, for example, 100 μm to 400 μm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-245990 [Patent Document 2] Japanese Patent Application Publication No. 2016-092040 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the pitch of electrodes on circuit boards has become increasingly narrow, with multiple electrodes sometimes formed at extremely small pitches of, for example, 100 μm or less. Conventional methods have made it difficult to solder conductor wires to electrodes formed at such extremely small pitches. For example, workers must solder each wire individually under a microscope or magnifying glass. Therefore, a connection method that allows for efficient soldering was needed. Furthermore, because narrow electrode pitches tend to cause solder bridges between electrodes, a connection structure that can prevent such bridges was also needed. Here, solder bridges refer to the occurrence of an electrical short circuit caused by solder bridging between adjacent electrodes.

[0005] The present invention has been made in view of the above circumstances, and its first object is to provide a connection method for efficiently connecting a plurality of conductor wires to a plurality of electrodes formed on a substrate, and its second object is to provide a connection structure that can connect a plurality of electrodes formed on a substrate at a very small pitch to a plurality of conductor wires while suppressing the occurrence of solder bridges. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides a method for connecting a plurality of conductor wires to a plurality of electrodes formed on a substrate, the conductor wire connecting method comprising: an arrangement step of arranging a single solid solder between the plurality of electrodes and the plurality of conductor wires; and a soldering step of melting the solid solder while pressing the plurality of conductor wires against the substrate, thereby soldering the plurality of electrodes to the plurality of conductor wires.

[0007] In order to solve the above-mentioned problems, the present invention provides a conductor wire connection structure that connects a plurality of electrodes formed at an extremely small pitch on a substrate to a plurality of conductor wires, wherein the plurality of electrodes and the plurality of conductor wires are respectively connected by solder, and the ends of the plurality of conductor wires on the outer surface opposite the plurality of electrodes are not covered by the solder. [Effects of the Invention]

[0008] The conductor wire connecting method according to the present invention makes it possible to efficiently connect a plurality of conductor wires to a plurality of electrodes formed on a substrate, and the conductor wire connecting structure according to the present invention makes it possible to connect a plurality of conductor wires to a plurality of electrodes formed on a substrate at an extremely small pitch while suppressing the occurrence of solder bridges. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view showing a conductor wire connection structure according to an embodiment of the present invention; [Figure 2] 1 is a perspective view illustrating components of a conductor wire connection structure according to an embodiment of the present invention. [Figure 3] 1(a) is a plan view of the substrate, showing first to fifth electrodes formed on the substrate, viewed from a direction perpendicular to the base material, and FIG. 1(b) is a cross-sectional view taken along line AA in FIG. [Figure 4] 1(a) is a diagram showing a state in which solder foils are placed on the first to fifth electrodes, and FIG. 1(b) is a cross-sectional view taken along line BB in FIG. [Figure 5] 1(a) is a diagram showing a state in which the conductor wires of the first to fifth electric wires are arranged on a solder foil, and FIG. 1(b) is a cross-sectional view taken along line CC in FIG. [Figure 6] 1(a) is a diagram showing a state in which the conductor wire is pressed against the substrate by the heater chip and solder foil is sandwiched between the conductor wire and the first to fifth electrodes, and FIG. 1(b) is a cross-sectional view taken along line DD in FIG. 1(a). [Figure 7] 1A is a diagram showing a state in which the solder foil is melted by energizing the heater chip, and FIG. 1B is a cross-sectional view taken along line EE in FIG. [Figure 8] 1(a) is a diagram showing a state in which the solder has solidified and the soldering of the conductor wires to the first to fifth electrodes has been completed, and FIG. 1(b) is a cross-sectional view taken along line FF in FIG. [Figure 9] This is an enlarged view of FIG. 8(b). [Figure 10]FIG. 8(b) is a cross-sectional view taken along line GG in FIG. 8(a). DETAILED DESCRIPTION OF THE INVENTION

[0010] [Embodiment Mode] Fig. 1 is a perspective view showing a conductor wire connection structure according to an embodiment of the present invention. Fig. 2 is a perspective view illustrating components of the conductor wire connection structure according to the embodiment of the present invention. This conductor wire connection structure connects first to fifth electrodes 11-15 formed on a substrate 1 to conductor wires 211, 221, 231, 241, and 251 of first to fifth electric wires 21-25. The substrate 1 and the first to fifth electric wires 21-25 are used as components of electronic products whose commercial value is enhanced by their high integration density and small size, such as endoscopes and wearable devices.

[0011] The substrate 1 is a flexible substrate having a flexible, flat-plate-shaped substrate 10 made of polyimide or the like. In FIGS. 1 and 2, first to fifth electrodes 11 to 15 are formed on one surface 10a of the strip-shaped substrate 10 at one end in the longitudinal direction. The first to fifth electrodes 11 to 15 are pad electrodes formed by etching copper foil attached to the surface of the substrate 10 into a predetermined shape. Note that, although wiring patterns and vias are formed on the substrate 1 to connect the first to fifth electrodes 11 to 15 with electronic components, the wiring patterns and vias are not shown in FIGS. 1 and 2 and in the drawings described below.

[0012] The first to fifth electric wires 21 to 25 are insulated-coated electric wires in which conductor wires 211, 221, 231, 241, and 251 serving as core wires are covered with insulators 212, 222, 232, 242, and 252. The conductor wires 211, 221, 231, 241, and 251 are made of, for example, copper or a copper alloy. In this embodiment, the conductor wires 211, 221, 231, 241, and 251 are solid wires having a circular cross section, but this is not limiting and they may also be stranded wires made by twisting together a plurality of conductor wires. The insulators 212, 222, 232, 242, and 252 are made of, for example, fluororesin or polyester resin. The first to fifth electric wires 21 to 25 have the insulators 212, 222, 232, 242, and 252 removed at their ends, so that the conductor wires 211, 221, 231, 241, and 251 are exposed.

[0013] The first to fifth electrodes 11-15 are formed at a very small pitch along the arrangement direction, which corresponds to the short side direction of the substrate 10. The conductor wires 211, 221, 231, 241, and 251 of the first to fifth electric wires 21-25 are connected to the first to fifth electrodes 11-15 by solders 31-35, respectively. The solders 31-35 are made of a low-melting-point conductive metal containing, for example, tin as a main component, and are interposed between the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251 of the first to fifth electric wires 21-25, joining the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251.

[0014] If the amount of solder 31-35 on the first to fifth electrodes 11-15, which are formed at a very small pitch, is too large, solder bridges are likely to occur, and if it is too small, the bonding strength between the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251 will be weak. For this reason, it is desirable that the amount of solder 31-35 on each of the first to fifth electrodes 11-15 be uniform and be an amount that is appropriately interposed between the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251. Furthermore, for example, if the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251 are connected one by one by hand, the workload on the worker is heavy, and the time and cost required for the connection work will increase.

[0015] In this embodiment, the conductor wires 211, 221, 231, 241, and 251 of the first to fifth electric wires 21 to 25 are connected together to the first to fifth electrodes 11 to 15 formed on the substrate 1 by the connection method described below. In summary, this connection method involves placing a single solid solder between the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, and 251, and melting this solid solder to solder the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, and 251 together, respectively.

[0016] In this embodiment, a thin-film solder foil 30 shown in FIG. 2 is used as a single solid solder. The solders 31 to 35 shown in FIG. 1 are formed by melting and solidifying the solder foil 30. The thickness T1 of the solder foil 30 is, for example, 20 μm or less. If the thickness T1 of the solder foil 30 is too thin, it is difficult to handle and may weaken the bonding strength between the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, and 251. Therefore, the thickness T1 of the solder foil 30 is preferably 1 μm or more. By setting the thickness T1 of the solder foil 30 to be 1 μm or more and 20 μm or less, an appropriate amount of solder 31 to 35 can be interposed between the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, and 251. A specific example of this connection method will be described in detail with reference to FIGS. 3 to 8.

[0017] FIG. 3(a) is a plan view of the substrate 1, showing the first to fifth electrodes 11 to 15 formed on the substrate 1, as viewed from a direction perpendicular to the base material 10. FIG. 3(b) is a cross-sectional view taken along line AA in FIG. 3(a). The first to fifth electrodes 11 to 15 are arranged in a row at equal intervals along the short side of the base material 10. When viewed from a direction perpendicular to the base material 10, the first to fifth electrodes 11 to 15 have a rectangular shape whose long side is aligned with the longitudinal direction of the base material 10. The pitch P of the first to fifth electrodes 11 to 15 is, for example, 100 μm or less. The spacing S of the first to fifth electrodes 11 to 15 is, for example, 50 μm or less.

[0018] In FIG. 3( a), the electrode formation region 100 in which the first to fifth electrodes 11 to 15 are formed is shown surrounded by a two-dot chain line. The electrode formation region 100 is a region that entirely surrounds the first to fifth electrodes 11 to 15. The length L1 of the electrode formation region 100 along the long side direction of the first to fifth electrodes 11 to 15 is the same as the length of the first to fifth electrodes 11 to 15 in the long side direction. The width W1 of the electrode formation region 100 along the arrangement direction of the first to fifth electrodes 11 to 15 corresponds to the distance between one end in the short side direction of the first electrode 11 (the end opposite the second electrode 12) and one end in the short side direction of the fifth electrode 15 (the end opposite the fourth electrode 14), which are both ends of the arrangement direction of the first to fifth electrodes 11 to 15.

[0019] FIG. 4(a) is a diagram showing a state in which the solder foil 30 is placed on the first to fifth electrodes 11 to 15. FIG. 4(b) is a cross-sectional view taken along line BB in FIG. 4(a). In FIG. 4(a), the outlines of the first to fifth electrodes 11 to 15 overlapping with the solder foil 30 are indicated by dashed lines. The solder foil 30 is rectangular and is large enough to cover at least a portion of each of the first to fifth electrodes 11 to 15. In this embodiment, the length L2 of the solder foil 30 along the long side direction of the first to fifth electrodes 11 to 15 is shorter than the length L1 of the electrode formation region 100, and the width W2 of the solder foil 30 along the arrangement direction of the first to fifth electrodes 11 to 15 is wider than the width W1 of the electrode formation region 100. However, the length L2 of the solder foil 30 may be the same as the length L1 of the electrode formation region 100, and the width W2 of the solder foil 30 may be the same as the length W1 of the electrode formation region 100.

[0020] Fig. 5(a) is a diagram showing a state in which the conductor wires 211, 221, 231, 241, and 251 of the first to fifth electric wires 21 to 25 are arranged on the solder foil 30. Fig. 5(b) is a cross-sectional view taken along line CC in Fig. 5(a). The first to fifth electric wires 21 to 25 are arranged on the substrate 1 so that the conductor wires 211, 221, 231, 241, and 251 overlap the first to fifth electrodes 11 to 15, with the solder foil 30 sandwiched therebetween.

[0021] Fig. 6(a) is a diagram showing a state in which the conductor wires 211, 221, 231, 241, and 251 are pressed against the substrate 1 by the heater chip 4 of the pulse heat unit, and the solder foil 30 is sandwiched between the conductor wires 211, 221, 231, 241, and 251 and the first to fifth electrodes 11 to 15. Fig. 6(b) is a cross-sectional view taken along line DD in Fig. 6(a). The heater chip 4 is a heating element that generates heat instantaneously when energized, and the width W3 of the tip surface 4a of the heater chip 4 that contacts the conductor wires 211, 221, 231, 241, and 251 is wider than the width W1 of the electrode formation region 100. This allows the heater chip 4 to press the conductor wires 211, 221, 231, 241, and 251 all together against the substrate 1, and sandwich the solder foil 30 between the conductor wires 211, 221, 231, 241, and 251 and the first to fifth electrodes 11-15.

[0022] FIG. 7(a) is a diagram showing a state in which the heater chip 4 is energized and the solder foil 30 is melted. FIG. 7(b) is a cross-sectional view taken along line EE in FIG. 7(a). The solder foil 30 melts and becomes liquid due to the heat of the heater chip 4 transmitted through the conductor wires 211, 221, 231, 241, and 251. Liquid solder is easily mixed with the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, and 251, which are made of metal, but is not easily mixed with the substrate 10 made of a resin such as polyimide. Therefore, the solder that has melted from the solder foil 30 and become liquid is dispersed between the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, and 251, becoming solders 31 to 35.

[0023] 8(a) is a diagram showing a state in which the solders 31 to 35 have solidified and the soldering of the conductor wires 211, 221, 231, 241, and 251 to the first to fifth electrodes 11 to 15 has been completed. FIG. 8(b) is a cross-sectional view taken along line FF in FIG. 8(a). When the power supply to the heater chip 4 is cut off, the temperature drops, and the solders 31 to 35 become solid due to the temperature drop. The heater chip 4 continues to press the conductor wires 211, 221, 231, 241, and 251 against the substrate 1 until the solders 31 to 35 solidify, and after the solders 31 to 35 have solidified, the heater chip 4 is separated from the conductor wires 211, 221, 231, 241, and 251.

[0024] Thus, the method of connecting the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, 251 in this embodiment includes an arrangement process of arranging solder foil 30, which is a single solid solder, between the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, 251, and a soldering process of melting the solder foil 30 while pressing the conductor wires 211, 221, 231, 241, 251 against the substrate 1, thereby soldering the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, 251, respectively.

[0025] In the soldering process, the conductor wires 211, 221, 231, 241, and 251 are pressed against the substrate 1 by the heater chip 4, and the solder foil 30 is sandwiched between the first to fifth electrodes 11 to 15 and the conductor wires 211, 221, 231, 241, and 251. In this state, heat from the heater chip 4 is transferred to the solder foil 30 via the conductor wires 211, 221, 231, 241, and 251 to melt the solder foil 30. In addition, in the soldering process, while the conductor wires 211, 221, 231, 241, and 251 are pressed against the substrate 1 by the heater chip 4, current is started to be applied to the heater chip 4 to melt the solder foil 30, and after the supply of current to the heater chip 4 is stopped, the heater chip 4 is separated from the conductor wires 211, 221, 231, 241, and 251.

[0026] Fig. 9 is an enlarged view of Fig. 8(b). The solders 31 to 35 solidify while the conductor wires 211, 221, 231, 241, and 251 are pressed against the substrate 1 by the heater chip 4, and therefore the solders 31 to 35 are not attached to the portions of the conductor wires 211, 221, 231, 241, and 251 that were in contact with the tip surface 4a of the heater chip 4. In other words, the end portions 211b, 221b, 231b, 241b, and 251b of the outer peripheral surfaces 211a, 221a, 231a, 241a, and 251a of the conductor wires 211, 221, 231, 241, and 251, respectively, that are opposite the first to fifth electrodes 11 to 15, are not covered with the solders 31 to 35.

[0027] Here, even if solder is attached to the ends 211b, 221b, 231b, 241b, and 251b of the outer peripheral surfaces 211a, 221a, 231a, 241a, and 251a of the conductor wires 211, 221, 231, 241, and 251, the solder attached to these portions does not contribute to the electrical conductivity or bonding strength between the conductor wires 211, 221, 231, 241, and 251 and the first to fifth electrodes 11 to 15. In other words, in this embodiment, by not attaching an unnecessary amount of solder to the conductor wires 211, 221, 231, 241, and 251, the occurrence of solder bridges is suppressed.

[0028] FIG. 10 is a cross-sectional view taken along line GG in FIG. 8(a). In FIG. 10, T2 denotes the thickness of the solder 31 interposed between the first electrode 11 and the end 211c of the outer surface 211a of the conductor wire 211 of the first electric wire 21. The thickness T2 is equal to or less than the thickness T1 of the solder foil 30 before melting, specifically, 20 μm or less, throughout the entire longitudinal direction of the conductor wire 211 soldered to the first electrode 11. The solder 31 interposed between the first electrode 11 and the end 211c of the outer surface 211a of the conductor wire 211 that is closer to the first electrode 11 contributes to improving the electrical conductivity and bonding strength between the conductor wire 211 and the first electrode 11. Furthermore, because the thickness T2 of the solder 31 in this portion is equal to or less than 20 μm, the amount of solder 31 is reduced, thereby suppressing the occurrence of solder bridges.

[0029] 9, the solder 32 to 35 interposed between the second to fifth electrodes 12 to 15 and the end portions 221c, 231c, 241c, 251c of the outer surfaces 221a, 231a, 241a, 251a of the conductor wires 221, 231, 241, 251 of the second to fifth electric wires 22 to 25 on the second to fifth electrodes 12 to 15 side, like the solder 31 shown in FIG. 10, has a thickness that is less than the thickness T1 of the solder foil 30 before melting, and is 20 μm or less, over the entire longitudinal direction of the conductor wires 221, 231, 241, 251 soldered to the second to fifth electrodes 12 to 15.

[0030] The conductor wires 211, 221, 231, 241, and 251 of the first to fifth electric wires 21 to 25 may be in contact with the first to fifth electrodes 11 to 15 at a portion in the longitudinal direction. In other words, the minimum thickness of the solder 31 to 35 between the conductor wires 211, 221, 231, 241, and 251 and the first to fifth electrodes 11 to 15 may be zero.

[0031] (Effects of the embodiment) According to the embodiment described above, a single solid solder disposed between the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251 is melted to solder the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251 all at once, thereby reducing the time and cost required for soldering compared to, for example, manually soldering each wire. While the solid solder may be, for example, a single wire solder disposed across the first to fifth electrodes 11-15, in this embodiment, a thin-film solder foil 30 is used as the solid solder, thereby enabling uniform and approximately constant amounts of solder 31-35 to be formed between the first to fifth electrodes 11-15 and the conductor wires 211, 221, 231, 241, and 251 in the longitudinal direction of the first to fifth electrodes 11-15. This prevents the occurrence of solder bridges, and eliminates the need to wait for the molten solder to flow in the longitudinal direction of the first to fifth electrodes 11 to 15 and spread between the conductor wires 211, 221, 231, 241, and 251, allowing soldering to be completed in a short time.

[0032] Furthermore, according to this embodiment, the heater chip 4 presses the conductor wires 211, 221, 231, 241, 251 toward the substrate 1, and the solder foil 30 is melted while being sandwiched between the conductor wires 211, 221, 231, 241, 251 and the first to fifth electrodes 11 to 15. This prevents the conductor wires 211, 221, 231, 241, 251 from floating up from the first to fifth electrodes 11 to 15, and allows the conductor wires 211, 221, 231, 241, 251 to be properly connected to the first to fifth electrodes 11 to 15 with a small amount of solder.

[0033] Furthermore, according to this embodiment, the supply of current to the heater chip 4 is stopped and the solder 31 to 35 is solidified, and then the heater chip 4 is separated from the conductor wires 211, 221, 231, 241, and 251. This prevents the molten solder from adhering to the heater chip 4 and also prevents the solder 31 to 35 from solidifying in a state where the conductor wires 211, 221, 231, 241, and 251 are floating above the first to fifth electrodes 11 to 15.

[0034] Furthermore, according to this embodiment, the ends 211b, 221b, 231b, 241b, 251b of the outer surfaces 211a, 221a, 231a, 241a, 251a of the conductor wires 211, 221, 231, 241, 251 opposite the first to fifth electrodes 11 to 15 are not covered with solder 31 to 35, so the amount of solder 31 to 35 is reduced and the occurrence of solder bridges is suppressed.

[0035] Furthermore, according to this embodiment, the thickness of the solder 31 to 35 interposed between the end portions 211c, 221c, 231c, 241c, 251c on the outer surfaces 221a, 231a, 241a, 251a of the conductor wires 211, 221, 231, 241, 251 of the first to fifth electric wires 21 to 25 on the first to fifth electrodes 11 to 15 side and the first to fifth electrodes 11 to 15 is 20 μm or less throughout the entire longitudinal direction of the conductor wires 211, 221, 231, 241, 251 in the portions soldered to the first to fifth electrodes 11 to 15. Therefore, electrical conductivity and bonding strength can be ensured with a small amount of solder 31 to 35, and the occurrence of solder bridges is also suppressed.

[0036] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0037] [1] A method for connecting a plurality of conductor wires (211, 221, 231, 241, 251) to a plurality of electrodes (11 to 15) formed on a substrate (1), the conductor wire connecting method comprising: a placement step of placing a single solid solder (30) between the plurality of electrodes (11 to 15) and the plurality of conductor wires (211, 221, 231, 241, 251); and a soldering step of melting the solid solder (30) while pressing the plurality of conductor wires (211, 221, 231, 241, 251) against the substrate (1), thereby soldering the plurality of electrodes (11 to 15) to the plurality of conductor wires (211, 221, 231, 241, 251), respectively.

[0038] [2] The conductor wire connecting method according to [1] above, wherein the solid solder is a thin-film solder foil (30), and in the soldering process, the solder foil (30) is melted while being sandwiched between the plurality of electrodes (11 to 15) and the plurality of conductor wires (211, 221, 231, 241, 251).

[0039] [3] The conductor wire connecting method described in [2] above, wherein in the soldering process, the plurality of conductor wires (211, 221, 231, 241, 251) are pressed against the substrate (1) by a heating element (4), and heat from the heating element (4) is transferred to the solder foil (30) via the conductor wires (211, 221, 231, 241, 251) to melt the solder foil (30).

[0040] [4] The conductor wire connecting method according to [3] above, wherein the heating element is a heater chip (4) that generates heat when current is applied, and in the soldering step, the heater chip (4) presses the plurality of conductor wires (211, 221, 231, 241, 251) against the substrate (1) to melt the solder foil (30), and after stopping the supply of current to the heater chip (4), the heater chip (4) is separated from the plurality of conductor wires (211, 221, 231, 241, 251).

[0041] [5] A conductor wire connecting method according to any one of [2] to [4] above, wherein the solder foil (30) is large enough to cover at least a portion of each of the plurality of electrodes (11 to 15) collectively.

[0042] [6] The conductor wire connecting method according to any one of the above [2] to [4], wherein the thickness (T1) of the solder foil (30) is 20 μm or less.

[0043] [7] The conductor wire connecting method according to the above [1], wherein the pitch (P) of the plurality of electrodes (11 to 15) is 100 μm or less.

[0044] [8] A connection structure between a plurality of electrodes (11 to 15) formed at a very small pitch on a substrate (1) and a plurality of conductor wires (211, 221, 231, 241, 251), wherein the plurality of electrodes (11 to 15) and the plurality of conductor wires (211, 221, 231, 241, 251) are connected by solder (31 to 35), respectively, and end portions (211b, 221b, 231b, 241b, 251b) on the outer peripheral surfaces (211a, 221a, 231a, 241a, 251a) of the plurality of conductor wires (211, 221, 231, 241, 251) opposite to the plurality of electrodes (11 to 15) are not covered with the solder (31 to 35).

[0045] [9] The conductor wire connection structure according to [8] above, wherein the thickness (T2) of the solder (31-35) interposed between the end portions of the outer surfaces (211a, 221a, 231a, 241a, 251a) of the plurality of conductor wires (211, 221, 231, 241, 251) on the side of the plurality of electrodes (11-15) and the plurality of electrodes (11-15) is 20 μm or less over the entire longitudinal direction of the plurality of conductor wires (211, 221, 231, 241, 251) in the portions soldered to the plurality of electrodes (11-15).

[0046]

[10] The conductor wire connection structure according to [8] or [9] above, wherein the plurality of conductor wires (211, 221, 231, 241, 251) are the core wires of a plurality of insulated electric wires (21 to 25) each having a core wire covered with an insulator (212, 222, 232, 242, 252).

[0047] (Addendum) Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented without departing from the spirit of the invention, and for example, the following modifications are possible.

[0048] In the above embodiment, the conductor wires 211, 221, 231, 241, 251 connected to the first to fifth electrodes 11 to 15 are described as core wires of the electric wires 21 to 25. However, the present invention is not limited to this, and can also be applied to, for example, connecting the center conductor of a coaxial cable to an electrode formed on a substrate, or connecting the lead frame of an electronic component formed by sealing an IC chip with a sealant to an electrode formed on a substrate. In this case, the center conductor or the lead frame corresponds to the conductor wire of the present invention.

[0049] Furthermore, in the above embodiment, the first to fifth electrodes 11 to 15 are described as being formed in a row at equal intervals along the short side direction of the strip-shaped substrate 10, but the shape of the substrate and the arrangement of the electrodes on the substrate are not limited to those exemplified in the description of the embodiment, and can be modified as appropriate depending on the application, function, etc. of the product.

[0050] Furthermore, in the above embodiment, the case where the number of electrodes is five has been described as an example, but the number of electrodes formed on the substrate is not limited to this, and may be four or less or six or more. Furthermore, when there are a large number of electrodes, the electrodes may be divided into multiple blocks, and each block may be connected to a conductor wire using the connection method of the present invention. For example, when there are 100 electrodes, these electrodes may be divided into blocks of five to ten electrodes, and each block may be connected to a plurality of conductor wires using a connection method using solder foil.

[0051] Furthermore, in the above embodiment, the present invention can be particularly suitably used when the electrode pitch is 100 μm or less, but it can also be applied when the electrode pitch is wider than 100 μm, for example, 200 μm or less or 500 μm or less. [Explanation of symbols]

[0052] 1...Substrate 11 to 15: First to fifth electrodes 22~25...1st to 5th electric wires 211, 221, 231, 241, 251...Conductor wire 211a, 221a, 231a, 241a, 251a...outer surface 211b, 221b, 231b, 241b, 251b...end 211c, 221c, 231c, 241c, 251c...end 212, 222, 232, 242, 252...insulators 30...Solder foil (solid solder) 31~35...Solder 4...Heater chip (heating element)

Claims

1. A method for connecting a plurality of conductor wires to a plurality of electrodes formed on a substrate, the method comprising the steps of: a placement step of placing a single solid solder between the plurality of electrodes and the plurality of conductor wires; a soldering step of melting the solid solder while pressing the plurality of conductor wires against the substrate to solder the plurality of electrodes to the plurality of conductor wires, respectively; A conductor wire connecting method comprising:

2. the solid solder is a thin film solder foil, In the soldering step, the solder foil is melted while being sandwiched between the plurality of electrodes and the plurality of conductor wires. The conductor wire connecting method according to claim 1 .

3. In the soldering step, the plurality of conductor wires are pressed against the substrate by a heating element, and heat from the heating element is transferred to the solder foil via the conductor wires to melt the solder foil. The conductor wire connecting method according to claim 2 .

4. the heating element is a heater chip that generates heat when energized, In the soldering step, the heater chip presses the plurality of conductor wires against the substrate to melt the solder foil, and then the heater chip is separated from the plurality of conductor wires after stopping the supply of current to the heater chip. The conductor wire connecting method according to claim 3.

5. The solder foil has a size that collectively covers at least a portion of each of the plurality of electrodes. The conductor wire connecting method according to any one of claims 2 to 4.

6. The thickness of the solder foil is 20 μm or less. The conductor wire connecting method according to any one of claims 2 to 4.

7. The pitch of the plurality of electrodes is 100 μm or less. The conductor wire connecting method according to claim 1 .

8. A connection structure between a plurality of electrodes formed at a very small pitch on a substrate and a plurality of conductor wires, the plurality of electrodes and the plurality of conductor wires are connected by solder, the ends of the outer circumferential surfaces of the conductor wires opposite to the electrodes are not covered with the solder; Conductor wire connection structure.

9. a thickness of the solder interposed between the ends of the conductor wires on the outer peripheral surfaces thereof on the side of the electrodes and the electrodes is 20 μm or less over the entire longitudinal direction of the conductor wires in the portions soldered to the electrodes; The conductor wire connection structure according to claim 8 .

10. The plurality of conductor wires are the core wires of a plurality of insulation-coated electric wires each having a core wire coated with an insulator. The conductor wire connection structure according to claim 8 or 9.

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